A national park ranger puts up a sign beside the footpath leading to the Plateau de Longon to warn hikers about the patou dogs that protect flocks of sheep grazing on the mountain, Mercantour National Park, French Alps, France, 01 August 2013. The sign reads "If the dogs come towards you, stop. Don't shout, don't throw stones. After observing you for a while, they [the dogs] will generally leave of their own accord"